Immersion starter for pool-type discharge devices



Feb. 8, 1938. I E upp 2,107,908 I IMMERSION STARTER FOR POOL TYPEDISCHARGE DEVICES Filed Oct. 31, 1955 Inventor: Emil Rup'p,

Patented Feb. 8,1938 I i I IMIVIERSION STARTER FOR POOL-TYPE DISCHARGEDEVICES Emil Rupp, Berlin-Frohnau, Germany, assignor to General ElectricCompany, acorporation of New York e Application October 31, 1935, SerialNo. 47,694 g In Germany November 8, 1934 2 Claims. (01. 25027.5)

,My invention relates to an improved immerat the same time a positivevoltage on the anode 2.

sion starter for pool-type discharge devices. As a material for theconstruction of my im- It is now known that an arc discharge betweenproved immersion electrode I have found that a mercury pool cathode andan anode spaced graphite rods having a graphite content not in 5therefrom can be initiated with great facility by excess of 80 per centand a complementary promeans of an immersion electrode of .asemi-conportion of clay have many outstanding advanducting material suchas silicon or tungsten cartages. The graphite may vary from the maxibidehaving its tip projecting below the surface mum value stated down toaminimum of about 20 of the mercury pool. While the nature of the percent, the composition being chosen to causestarting phenomenon is notentirely understood, the specific resistivity to fall between about 10010 it is found to differ fundamentally both in efand about 100,000 timesthat of mercury. While fectiveness and in amount of required startingthe electrode rod may assume various shapes, I current from thatobtained by the use of a meprefer to have it pointed at the active endwhich tallic filament projecting into the mercury such is then immersedin the mercury to a depth of as is shown, for example, in Bodde PatentNo. several millimeters. The depth of immersion may 5 832,363. 1 beadjusted by corresponding adjustment of the n r t iebelieVe-d t e ar g equantity of mercury in the cathode pool. feet of the new immersionelectrode depends in .Since an unpredictable quantity of the merpa upont a e of th ae between, its cury will vaporize during operation of thetube S rface a e adjoining erc y a n part, and remain adhering to theenvelope wall, un-

up n e Creation of a high potential gradient desirable variations in thestarting current may alo g" t e electrode y- Immersion Starting, occur.In Fig. 2 I have represented a form of together with the theoreticalconsiderations starting electrode by means f which this diff w ch governits operation are discussed in a culty may be overcome. As illustrated,the graph- 5. article by J- slepian d Ludwlsappearmg ite rod 6 issurrounded by a tube 1 of glass, at pa'ge 693 of V0]. 52 of theTransactwns of the quartz, or a similar t withstanding 1 1 1 A.I. E. E.for June, 1933. ing material from which the rod projects very I j ItY San O jec of the present invention to P slightly, say a few tenths of amillimeter. Above vide an immersion electrode characterized by rethmercury th electrode comprises an exposed quiring a lower startingcurrent than those conductive portion consisting in the present in- 30 areferring to the following specification taken in 5 cury pool cathode 3adapted to cooperate in con- 5, in the a u e of Such tubes accurateviously e p y and by E eater freedom from stance of an enlargedextension 8 of the graphite starting variations. core in combinationwith the clamp-like ex- An understanding of the further ob ects andtremity of the conductor The depending advant e of my invention may beobtained by tion of the electrode projects downward a sufficientdistance so that the core is exposed to the 35 mercury only below thesurface thereof. This arrangement, which is applicable to othersemiconducting starting materials than graphite, has

, connection with the accompanying drawing in which Fig. 1 illustratesan electric discharge device suitable for use with my invention, wh leFig. 2 is a fragmentary section of the tube of Fig. the advanta th t f tL f Start ge a e ec ive startmg can be a ggg gg i a preferred form 0complished with different depths of immersion 40 7 Referringparticularly to Fig. 1, I have shown up to at abPut 5 imeters. Forthis athree-electrode discharge device comprising an reason Varlatlons tmercury level fail to envelope I which contains an anode 2 and amerefiect the r q e lgnltlon current. n quentducting an arc-likedischarge through the tub adjustment of the cathode pool is unnecessaryStarting of the discharge is accomplished by passand he Irregularcondensatlon of the p l n h 'ing current through the lead-in connection4 and: e v p Wall Plays y a Subordinate part.

theimmersion electrode 5. This latter consists W e I have Shown a pa u eme t essentially of a mixture of clay and graphite and of y invention, tWill f course be understood 50 h t i k s of say, 1 to 2 in t and that Ido not wish to be limited thereto since length on the order of about 2centimeters. manymodifications in the structure may be made,

I When starting current ofpa few amperes flows and I contemplate by theappended claims to fromfthej immersion electrode into the mercury coverall such modifications as fall within the 55. pool a main discharge willtake place if there is true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:-

1. In an electric discharge device, an anode, a mercury pool cathode anda starting electrode supported in cooperative relation with saidcathode, said electrode comprising an exposed conductive portion abovesaid mercury pool and a depending portion projecting below the surfaceof the pool during the normal operation of the device, said last-namedportion consisting of an insulating sheath and a core of asemi-conducting material having a specific resistivity between about 100and 100,000 times that of mercury, the core being substantially enclosedby the sheath and being exposed to the mercury only below the surfacethereof.

2. In an electric discharge device, an anode, a mercury pool cathode anda starting electrode supported in cooperative relation with saidcathode, said electrode comprising an exposed conductive portion abovesaid mercury pool and a portion projecting below the surface of the poolduring the normal operation of the device, said last-named portioncomprising an insulating sheath and a core of semi-conducting materialhaving a specific resistivity between about 100 and 100,000 times thatof mercury,'the core being substantially enclosed by the sheath buthaving a tip projecting therethrough into contact with the mercury belowthe surface thereof.

EMIL RUPP.

